#include<iostream>
#include<vector>
#include<queue>
#include<cstring>
#include<cmath>
#include<map>
#include<set>
#include<cstdio>
#include<algorithm>
#define debug(a) cout<<#a<<"="<<a<<endl;
using namespace std;
const int maxn=2e5+1000;
typedef long long LL;
inline LL read(){LL x=0,f=1;char ch=getchar();	while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
return x*f;}
char str[maxn],t[maxn];
int main(void){
   cin.tie(0);std::ios::sync_with_stdio(false);
   LL n,k;cin>>n>>k;
   for(LL i=1;i<=n;i++) cin>>str[i];
   for(LL i=1;i<=k;i++) t[i]=str[i];
   for(LL i=1;i<=k;i++){
       for(LL j=i;j<=n;j+=k) t[j]=t[i];
   }
   if(strcmp(t+1,str+1)>=0){
      cout<<n<<"\n"<<(t+1)<<"\n";
   }
   else{
      for(LL i=k;i>=1;i--){
          if(t[i]!='9'){
             t[i]++;break;
          }
          else{
             t[i]='0';
          }
      }
      for(LL i=1;i<=k;i++){
          for(LL j=i;j<=n;j+=k) t[j]=t[i];
      }
      cout<<n<<"\n"<<(t+1)<<"\n";
   }
   return 0;
}
